Maximum Power Point Tracking Study Of PV Systems Under Local Shading

With the continuous development of society and technology,the drawbacks of traditional fossil energy sources are becoming more and more prominent,making new energy generation such as solar and wind power gaining more and more attention worldwide.Among them,solar energy has received more attention from scholars because of its easy access,abundant reserves and wide distribution.As the technology used in PV power generation is not mature enough in many aspects,the efficiency of PV power generation is relatively low,and the Maximum Power Point Tracking(MPPT)technology,as one of the means to effectively improve PV power generation,has important MPPT is of great importance as a means to improve the efficiency of PV power generation.Based on this,this paper investigates the MPPT technology for PV systems in complex environments to improve the power generation efficiency of PV systems.In this paper,the principle of PV cell is analyzed and the simulation model of PV cell is built.The output characteristics of PV cells are analyzed by different light intensity and ambient temperature,and the mechanism of multi-peak phenomenon in PV arrays under partial shadow environment is analyzed,and a series PV array is built for simulation comparison.The principles of several common MPPT methods are introduced,and a variable-step incremental conductance method is proposed by analyzing the advantages and disadvantages of different control methods.This method improves the tracking accuracy and speed in the simulation of single PV cell model compared with the conventional conductance increment method.For the conventional MPPT control method cannot better meet the control demand of maximum point tracking,this paper proposes an improvement method based on the cuckoo algorithm.By introducing the adaptive variation formula of step control coefficient and Lévy flight index to achieve the demand of step length in different iteration periods,and proposing a nonlinear variation scheme for the nest destruction rate P_ato make the algorithm increase the number of nest updates in the early stage to extend the global search range,and reduce the computation in the later stage to speed up the convergence speed.The performance of the improved algorithm is tested by selecting four standard international test functions.The test results show that the improved cuckoo algorithm achieves better results in both global search capability and convergence speed.To improve the efficiency of the PV system in the local shading environment,a composite control strategy based on the combination of the improved cuckoo algorithm and the variable step conductance increment method is proposed in this paper on the basis of the above improvements.The improved cuckoo algorithm is used to track the output power to near the maximum point with the advantage of strong global search ability and not easy to fall into the local optimal point,and then switch to the variable-step conductance increment method to further improve the local convergence characteristics and enhance the stability of local convergence.Finally,a 10*4 PV array is built in Matlab/Simulink with Boost boost circuit and PWM controller to complete the MPPT control,and simulations are conducted in static and dynamic lighting environments.